This application is based on application No. H11-151658 filed in Japan, the content of which is hereby incorporated by reference.
1. Field of the Invention
The present invention relates to a recording apparatus for receiving a broadcast program and recording the broadcast program onto a recording medium, a transmitting apparatus for transmitting a broadcast program, and a computer-readable recording medium.
2. Background Art
In recent years, digitized broadcast programs are being broadcast on more and more services. Due to the high cost of producing digitized broadcast programs, producers wish to restrict the recording of the digitized broadcast programs. On the contrary, consumers want to record the digitized broadcast programs onto recording media for later use. To strike a balance between these mutually contradictory needs, men of learning and researchers have proposed a technique for embedding information concerning copyright protection (copy control information) into broadcast programs as electronic watermarks.
The object of the present invention is to provide a recording apparatus for performing, if copy control information is embedded into a broadcast program as electronic watermarks, the recording of the broadcast program according to the electronic watermarks.
The following description concerns an example broadcasting system including the recording apparatus of the present invention. The construction of the present broadcasting system is shown in FIG. 1. This system includes a transmitting apparatus 500 and a recording apparatus 600. The transmitting apparatus 500 includes a watermark embedding unit 501 and a transmitting unit 502. The watermark embedding unit 501 embeds a set of electronic watermarks into each video section composing a broadcast program. The electronic watermark set shows whether the recording of the broadcast program is permitted or prohibited and each video section of the broadcast program corresponds to, for instance, a reproduction time period of ten seconds. The transmitting unit 502 transmits the broadcast program where the watermark embedding unit 501 has embedded the electronic watermark set into each video section.
The recording apparatus 600 includes a receiving unit 601, a recording unit 602, a watermark reading unit 603, and a control unit 604.
The receiving unit 601 receives a broadcast program and the recording unit 602 records the received broadcast program onto a recording medium. The watermark reading unit 603 reads electronic watermarks from the received broadcast program and the control unit 604 instructs the recording unit 602 to record or not to record the received broadcast program according to the read electronic watermarks.
The operation of the recording apparatus 600 is described in detail below. After the receiving unit 601 starts to receive a broadcast program, the watermark reading unit 603 reads the electronic watermark set embedded into the first received video section, out of video sections composing the broadcast program. If the electronic watermark set shows that the recording of the broadcast program is permitted, the control unit 604 instructs the recording unit 602 to record video sections following the first received video section. On the other hand, if the electronic watermark set shows that the recording is prohibited, the control unit 604 instructs the recording unit 602 not to record the following video sections.
By operating in this manner, the recording apparatus 600 controls the recording of broadcast programs onto recording media as intended by producers of the broadcast programs.
The following description concerns the case where the recording apparatus is currently receiving a broadcast program B whose recording is prohibited and so does not perform the recording operation, and a broadcast program A into which electronic watermarks showing that recording is permitted are embedded is newly selected. Even if the embedded electronic watermarks show that recording is permitted, the recording apparatus 600 cannot start to record the broadcast program A until the recording apparatus 600 reads an electronic watermark set from the first received video section of the broadcast program A and finds that the recording of the broadcast program A is permitted by referring to the embedded electronic watermarks and must not perform the recording operation until it becomes clear that the embedded electronic watermarks show that recording is permitted. Because the recording apparatus 600 cannot immediately start to record the broadcast program A due to the reason given above, the first video section of the broadcast program A is not recorded onto a recording medium, that is, the program A recorded onto the recording medium lacks the first video section.
While an operator will take it for granted that the broadcast program A is entirely recorded onto the recording medium because the recording is permitted, the recorded broadcast program will lack the first video section. This may have the operator inappropriately suspect that the recording apparatus is out of order.
This problem will also arise in the case where the broadcast program B, whose recording is prohibited, is aired immediately before the broadcast program A, whose recording is permitted, the recording apparatus 600 is programmed to record the broadcast program A, and the internal clock of the recording apparatus 600 is wrong. In such a case, the recording apparatus starts the recording operation earlier than the broadcast start time of the broadcast program A. Therefore, the watermark reading unit 603 reads electronic watermarks from the broadcast program B and the control unit 604 instructs the recording unit 602 not to record the following video sections according to the read electronic watermarks. As a result, the first video section of the broadcast program A cannot be recorded, like the case above.
This problem will also arise if the recording apparatus 600 switches from the non-recordable broadcast program B to the recordable broadcast program A while viewing and recording broadcast programs.
To achieve the stated object of the present invention, the recording apparatus is required to record an entire broadcast program, including copy control information showing permission to record, onto a recording medium even when an immediately preceding broadcast program includes copy control information showing that recording is prohibited.
The stated requirement is satisfied by a recording apparatus for selecting one of a plurality of broadcast programs and recording the selected broadcast program onto a recording medium, each broadcast program being composed of a plurality of video sections into each of which is embedded an electronic watermark showing whether recording of the broadcast program is permitted or prohibited, the recording apparatus including: a receiving unit for receiving video sections composing the selected broadcast program one at a time; a recording unit for performing a recording operation according to instructions; a reading unit for reading an electronic watermark from each video section received by the receiving unit; and an instructing unit for issuing (a) a first instruction to have the recording unit record a video section next to the video section from which the electronic watermark has been read if the read electronic watermark shows that recording of the selected broadcast program is permitted and (b) a second instruction to have the recording unit not record the next video section if the read electronic watermark shows that the recording is prohibited, where the instructing unit includes an instruction changing unit for canceling, when another broadcast program is selected after the second instruction has been issued, the second instruction and issuing a third instruction to have the recording unit record a video section, out of video sections of the other broadcast program, to be received first.
When a next broadcast program is selected, the recording apparatus starts to record the broadcast program onto the recording medium without waiting for an electronic watermark to be read from the firstly received video section of the broadcast program. Consequently, if the next broadcast program is selected with the currently received broadcast program including an electronic watermark showing that recording is prohibited (which means that the recording unit has been instructed not to record the following video sections), the recording apparatus will start to record the next broadcast program as soon as the next broadcast program is selected. As a result, the next broadcast program is recorded onto the recording medium from the first video section to be received.
Here, the recording apparatus may further include a selection receiving unit for receiving a selection of the other broadcast program from an operator, where the instruction changing unit issues the third instruction when the selection receiving unit receives the selection.
Here, the recording apparatus may further include: a time information generating unit for, when the selection receiving unit receives the selection after the second instruction has been issued, generating first time information that shows when the selection receiving unit receives the selection; and a time information storing unit for storing the time information.
Here, when the selection receiving unit receives a further selection of a broadcast program different than the other broadcast program, the time information generating unit may generate second time information showing when the selection receiving unit receives the further selection, and the recording apparatus may further include: a difference calculating unit for calculating a difference between the first time information and the second time information; and a judging unit for judging whether the difference exceeds the predetermined time period, the instruction changing unit issues a fourth instruction to have the recording unit record a video section, out of video sections of the different broadcast program, to be firstly received.
Here, the recording apparatus may further include: a broadcast start time prestoring unit for prestoring a broadcast start time of a specific broadcast program; a time measuring unit for measuring a current time; and a selection unit for selecting the specific broadcast program, when the current time measured by the time measuring unit matches the broadcast start time prestored in the broadcast start time prestoring unit, where when the selection unit selects the specific broadcast program, the instruction changing unit issues a fifth instruction to have the recording unit record a video section, out of video sections of the specific broadcast program, to be firstly received. With this construction, the recording apparatus calculates the interval between the selection of a broadcast program whose recording is permitted and the selection of another broadcast program whose recording is prohibited and judges whether the interval exceeds a predetermined time period. If the interval is shorter than the predetermined time period, the recording apparatus does not reset the recording unit.
In this manner, the recording apparatus protects the copyrights on broadcast programs from a malicious third party who tries to record a broadcast program whose recording is prohibited onto a recording medium by frequently switching between the broadcast program and another broadcast program whose recording is permitted.